U.S. Pat. No. 4,489,268 describes a rechargeable battery containing a plurality of rechargeable electrochemical cells confined in a battery housing. The rechargeable battery includes first and second power terminal contacts disposed at opposite ends of the battery which are adapted to engage corresponding terminals in the energy-using device. The battery is adapted to be received by a cavity of the energy-using device which may be comprised, for example, a portable radio, television or tape recorder. When the energy-using device is operated in a first mode wherein it receives power from an external source of AC power, the charging circuit in the energy-using device provides charging current to the battery whereby the rechargeable battery is automatically recharged. When the energy-using device operates in a second battery powered mode, the load of the energy-using device receives power from the rechargeable batteries.
The over-all length of the rechargeable battery depicted in the '268 patent may be the same as the over-all length of a plurality of standard size non-rechargeable batteries such as standard AAA, AA, C or D size batteries. Hence, a user of the energy-using device, rather than employing the rechargeable battery taught in the '268 patent to provide battery power to the load of the energy-using device, may instead employ a plurality of individual standard size non-rechargeable batteries connected in series to provide battery power. In order to prevent such non-rechargeable batteries from being charged in the energy-using device during operation in the aforementioned first mode, the charging circuit within the energy-using device is provided with a charging terminal contact which engages a circumferentially extending charging terminal contact ring supported on the battery housing confining the individual rechargeable cells. The non-rechargeable batteries, having neither a housing confining a plurality of batteries nor the charging terminal contact ring on the housing, will not contact the charging terminal contact in the charging circuit and hence will not be charged when inserted into the energy-using device.
The invention described in the '268 patent not only precludes charging of a plurality of series connected non-rechargeable batteries by the charging circuit in the energy-using device, but also precludes charging of a plurality of rechargeable batteries of the same general type, size and configuration as standard size non-rechargeable batteries. Charging is precluded because the standard size rechargeable batteries do not have the charging terminal contact ring. Since the individual rechargeable batteries are sold in the same general standard types, configurations and sizes of non-rechargeable batteries, a plurality of standard rechargeable batteries may be inserted in the energy-using device to deliver battery power to the load of the energy-using device. However, these standard rechargeable batteries will not be automatically charged by the charging circuit of the energy-using device. Accordingly, while a consumer who has purchased standard rechargeable batteries will be able to use the rechargeable batteries to provide battery power to the energy-using device, the consumer will not be able to charge the standard rechargeable batteries with the charging circuit in the energy-using device. The present invention addresses this problem.